1. Field of Invention
This invention relates to a method of constructing concrete structures in which special apparatus is used to raise concrete plates cast one on top of the other at ground level, thus forming roof and floors and utilizing the lifting motion to form concrete walls.
2. Description of Prior Art
A method, generally known as "Liftslab" has been around in the building industry for many years. The method is well known. Equally well known in the building industry is a method called "Slipform." The Liftslab method has been employed in highrise apartments, office buildings, parking garages and other multi-floor structures. The Liftslab method is usually combined with posttensioning in the concrete slabs to enable the slabs to be thinner and more flexible.
The Slipform method has been employed extensively and practically exclusively in the construction of silo's, observation towers, elevator shafts and other structures where simple high vertical walls or columns form the main structural element. In the Slipform method walls or other vertical elements are formed by casting concrete in a bottomless form that rises while the concrete is being placed. Both the Liftslab and Slipform methods have been combined with conventional methods and have been generally restricted to highrise structures.
The advantages of the above described methods are: one; that practically no formwork is needed to form the concrete, and two; that placing of concrete is simple and fast. The Liftslab method and the Slipform method have not been used to any significant extent in residential and other one- and two- story structures for reason that equipment cost has thus far not justified such use.